The invention relates to a device for producing flexographic printing sleeves starting from photopolymerizable sleeves comprising at least a clean-out unit, a drying device, and a post-exposure unit, wherein the flexographic printing sleeves are transported within the apparatus by means of a transport device, wherein the sleeves are mounted dually translationally in the longitudinal direction in the transport device. The invention further relates to a method for producing flexographic printing sleeves using this device.
The production of ready-to-print flexographic printing forms is a multi-step process. Photopolymerizable flexographic printing elements comprising a photopolymerizable elastomeric layer applied to a suitable substrate are used as starting materials. The substrate can be a polymer or metal film or can be cylindrical sleeves, for example sleeves made of polymeric materials or metals. Cylindrical sleeves to which a photopolymerizable layer or a printing layer is applied are called “sleeves”.
In a first step, the photopolymerizable layer is exposed to actinic light through a suitable mask to form an image according to the desired print design. The mask has areas that are impermeable to actinic light and areas that are permeable to actinic light. When the photopolymerizable layer is exposed, it polymerizes in the exposed areas, whereas it does not polymerize in the unexposed areas. The mask can be a photographic negative, for example, which is placed onto the photopolymerizable layer or a digitally imagable layer that is applied to the photopolymerizable layer, for example a laser-ablatable opaque layer into which a mask is written using a laser. Also, the digitally imagable layer can be a layer brought out on the photopolymerizable layer, the applied layer capable of being made opaque to UV light imaging, for example a layer written by an Inkjet printer or a radiation-sensitive layer that can be blackened in certain areas using a radiation source.
After imaging exposure, the unexposed areas of the layer are removed using a suitable solvent and the printing form is dried to remove residual solvent. Then, a post-treatment can follow, for example exposure with UV-A and/or UV-C light. Each of the steps outlined is carried out in suitable processing equipment. In order to guarantee as rapid and economical a production of printing forms as possible, there are known processing devices in which two or more of the processing steps mentioned can be automatically carried out in succession.
The disadvantage to the known processing devices is the comparatively high space requirements. They can typically be 8 to 13 m long. Further, for economic reasons, there continues to be a need to shorten processing times as much as possible.
U.S. Pat. No. 5,919,378 discloses a device for producing round printing forms. Here, sleeves exposed for imaging are placed in a supply magazine and forwarded to a clean-out device through a solvent vapor safety lock. From there, the sleeves can be transferred to a drying unit and optionally to a post-treatment unit for exposure with UV-C light using an inspection unit to which sleeves can be withdrawn for testing purposes, and finally transferred to an output magazine.
U.S. Pat. No. 5,919,378 further discloses a method for producing round printing forms, the method comprising the following processing steps—in the sequence given: Suction of solvent vapors, cleaning out, drying and post-treatment with UVA and UVC radiation, wherein the round printing form is transported between each of the steps. The space requirements for this device and the method given is also relatively high due to the presence of a separate solvent vapor safety lock and due to the suction of solvent vapors taking place prior to the actual clean out step. In addition, due to the relatively large length of the process with the presence of a solvent vapor safety lock, the process time for producing a ready-to-print sleeve is lengthened, reducing production capacity.
The object of the invention is therefore to provide a device for producing sleeves which is of compact a design as possible and which facilitates a rapid and reliable production of sleeves.
Accordingly, a device for producing flexographic printing sleeves is provided which comprises at least                (II) a clean-out unit for removing unexposed portions of image-exposed sleeves using cleaning agent,        (III) a drying unit for removing residual cleaning agent from the cleaned out sleeves, and        (IV) a post-exposure unit for re-exposing the sleeves with UV radiation, and wherein units (II), (III) and (IV) are arranged directly one after the other in the sequence given, the sleeves have length L and for the purposes of processing in the device are mounted concentrically on axles of length l by way of suitable support devices so that the sleeves can rotate during the processing, with the condition that I>L, and wherein furthermore each of units (II) and (IV) comprises a transport device (T) for transporting the sleeves into the unit and from there to the next respective unit or out of the device, and wherein                    the transport device (T) comprises two supports (H) for holding the axles of the sleeves mounted thereon, said axles extending out from both sides of the sleeves and said supports being disposed parallel to one another at a distance A, wherein for A, the following relationship holds; L<A≦l, and            wherein the supports (H) are mounted dually translationally in the longitudinal direction of the device.                        
In a preferred embodiment of the invention, each of the transport devices (T) comprises two transport arms disposed parallel to one another, wherein the transport arms are mounted in such a way that they can move in the longitudinal direction, and a support (H) is disposed on each of the transport arms, the supports able to move along the transport arms.
Furthermore, a method for producing flexographic printing sleeves using such an apparatus was found.